The CLKREQ# is an open drain, active low signal that is driven low by
the card to request reference clock.

Since the reference clock may be required by i.MX PCIe host too. To make
sure this clock is available even when the CLKREQ# isn't driven low by
the card(e.x no card connected), force CLKREQ# override active low for
i.MX PCIe host during initialization.

The CLKREQ# override can be cleared safely when supports-clkreq is
present and PCIe link is up later. Because the CLKREQ# would be driven
low by the card in this case.

[PATCH v1 1/2] PCI: dwc: Invoke post_init in dw_pcie_resume_noirq()
[PATCH v1 2/2] PCI: imx6: Add a method to handle CLKREQ# override

drivers/pci/controller/dwc/pci-imx6.c             | 35 +++++++++++++++++++++++++++++++++++
drivers/pci/controller/dwc/pcie-designware-host.c |  3 +++
2 files changed, 38 insertions(+)